Technical Abstract: Understanding hydrology is paramount for optimal ecologic function and management of headwater streams. The objective of this study was to characterize and compare headwater streams within the Upper Big Walnut Creek watershed in Ohio. Two channelized and two unchannelized streams were instrumented with flumes and stage recorders to measure hydrology. Data were collected on 10-minute intervals from January 1, 2005 to December 31, 2006. Sixteen hydrology response variables that described the magnitude, frequency, or rate of change were calculated. Differences in flow magnitudes (average, low, and high) were generally greater (P < 0.05) in the channelized streams compared to the unchannelized streams. Frequency of zero discharge and out of bank discharge was significantly (P < 0.05) greater in the unchannelized streams compared to the channelized streams. Zero discharge occurred in the summer and out of bank flows occurred in the winter. Rate of change variables indicated that channelized streams respond quicker to rainfall and have slower recession times than unchannelized streams. In contrast to expectations, unchannelized streams tend to be more ‘flashy’ than channelized streams. Channelized and unchannelized headwater streams in the Upper Big Walnut Creek watershed exhibit differences in hydrology during certain times of the year. Design and installation of management practices should consider the potential impacts of altering the stream hydrology.